92 grand caravan problem

[mamba]

i have a 92 grand caravan se with a 3.3 v6 fuel injected .

the problem is it will idle fine no problems but as soon as i start moving the problems begin. it will back fire these little bangs not loud ones just smal puff kinda ones .. now i noticed when i pull over and check out the motor where the air filter is its hissing loud . now i know you say well thats normal . no this is louder than normal with great pressure . its like its trying to breathe but cannot .. i replaced the plugs , and wires so far . i was wondering what should i replace next . see its not so much the backfiring. its when i give it a small bit of gas its like the motor starts giving up and dying down not doing what its supposed to do and go ... but when i give it full throttle let me tell you it moves like a banshee... over exageration but you get the point .. oh and i replaced the fuel filter .. and air filter .. im at a loss is there a sensor for the oxygen intake that would cuase it to have these symptoms ? forgot to add when its doing the hissing sound and i lift up on the plastic for the air filter soon as i do that the hissing gets real quiet and everything returns to normal i also took apart the whole iar filter assembly to make sure nothing was blocking and to my surprise nothing was blocking it . i hope everyone can make heads or tails of what im saying . and by the way nice forum im gunna be here a hell of alot

[gforster]

sounds like you have a vacuum leak to me. Have a good look around while it's running and check all hoses/connections. Check power brake booster as well for vacuum leaks. do you get a check engine light on the dash?

Geoff

[mamba]

nope no check engine light comes on while runing . i did take off the i think is the throttle position sensor .. i mean it hooks right up with the throttle . so i imagine its the sensor . well i cleaned it and the housing . so far it seems to run better . but i still get that strange pressure in the air filter compartment .. i also disconnected the battery for about 5 min to see if it would reset anything . i was thinking a vacum leak or a vacum hose stuck but i dont even know where to begin on that thing . you think maybe the timing could play any part on this . im gunna have it checked on saturday . "hopefully". its wierd though . it runs fairly decent now from me goofing with it .. but the part is strange when i shut it off and turn it back on it starts bucking for like the first few seconds but once i get it going it moves great ? i did right at the air filter hose on the right side where it connects into the motor i disconnected both of those sensors . when i did this it ran great check engine light was on but it wouldnt lemme lay the hammer down at all nothing past 3 grand . and i dont think it would go into OD.

[gforster]

Try sparaying throttle body cleaner into the throttle body - it is the part that the throttle blade is in. Pay close attention to the idle air bypass port - this is where the AIS motor can get gummed up and cause these symptoms. The bypass port will hiss loudly on these with any of the air cleaner apart although it's hard to guess as I'm not right there... You can't change the ignition timing on the 3.3 as it is a DIS (Distributorless) Ignition System. Also the Cam position sensor has been known to act up on 3.3/3.8's - it is on the front(passenger side) of the engine and fairly easy to change. Also the MAP sensor is located in that area and can cause this kind of trouble. I doubt your fuel supply is acting up as you have lots of power if you stuff your foot in... If the engine runs smoothly and well when you hammer it and has plenty of power I doubt you have major mechanical problems - it's gotta be something minor but correctly diagnosing is 90% of a mechanic's job. Let me know what you think,

Regards,
Geoff

[gforster]

If all this turns up nothing it might be best to go to either a dealer or a shop that has the snap on scanner (and knows how to use it) and do some test (Test the ais motor operation for starters) I'm tempted to think that's the problem but it's a $50 guess so that's why it would be worth the 1 hour shop charge to read/interpret live data stream values. This is where most (not all) dealerships shine because they see these things every day and usually have very good troublshooting skills built up.

Another 2cents
Geoff

[mamba]

im definatley going to run this by my mechanic tonight .. i say these are all great ideas and possibly you right . thank you very much for your help .. ill let you know how this goes